Conversion and coking of hydrocarbon oils



June 2.2,

1931. J. G. ALTHER CONVERSION AAND COKING OF HYDROCARBON QILS Filed July29, 1932 Fra Cz'ozla for @y Wig@ Patented June 22, 1937 UNITED STATSPATENT OFFICE CONVERSION AND COKING OF HYDRO- CARBON OILS ApplicationJuly 29,

1 Claim.

This invention particularly refers to an improved process and apparatusfor the conversion and coking of hydrocarbon oils wherein heavy cils,tars and similar materials of high cokeforming characteristics which maybe carried over or entrained by the vapors are separated from thevaporous products resulting from the coking operation, prior tofractionation of the vapors, and are returned directly to the cokingchamber for further treatment.

By separating tars and other heavy coke-forming materials from thevaporous products of the process, prior to the separation of lowerboiling oils or reflux condensate therefrom the return of such materialsto the heating coil, together with the reflux condensate, is prevented,obviating the deposition of coke in the heating coil due to thedecomposition of such materials therein. The invention also provides forthe return of the heavy tar-like material separated from the vaporsdirect to the coking chamber of the process wherein they are reduced tocoke by further treatment together with the fresh residual liquidproducts from the conversion zone of the system.

The adaption of the primary features of the invention is not limited toany specific form of process or apparatus as its features may proveadvantageous in' any type of coking system alf though they areespecially well adapted to use in processes of the type wherein theconversion of hydrocarbon oil is accompanied by reduction of theresidual liquid'conversion products to coke,V

particularly at reduced pressure, and wherein insufficiently convertedor yintermediate conversion products 'of the operation are returned tofurther conversion in a heating coil of the same system. v

The attached diagrammatic drawing illustrates one specific formofapparatus in which the process of the invention may be carried out. Itshould be borne in mind, however', that the apparatus here shown anddescribed represents only v one of the many types of apparatus in whichthe concept of the present invention may be applied. Referring `to thedrawing, raw oil charging stock for the'system is supplied through lineI and valve 2 to pumpf3 from which it is fed through line 4, valves 5and 6, heat exchanger 1, line 8 and valve 9 to heating coil I0. Anyother well known manner of supplying the raw oil charging stock tothesystem may, of course, be employed;-Whendesired, although other meansare notillustrated in the drawing.

vHeatingcoil t0 is located within ra furnace II of any suitableyform bymeans of which the oil 1932, Serial N0. 625,865*

supplied to the heating coil is heated to the desired conversiontemperature preferably at a substantial super-atmospheric pressure. Theheated oil is discharged from heating coil I0 through line I2 and, inthe case here illustrated, passes 5 preferably through valve i3 in thisline into the lower portion of reaction chamber I4 or may be divertedfrom line I2 through line I5 and valve I by means of which it isdirected into the upper portion of reaction chamber I4.

Reaction chamber I4, like coil I0, is preferably maintained at asubstantial super-atmospheric pressure by means of which the heated oilfrom heating coil I0, and more particularly its vaporous components, aresubjected to continued conversion time in the reaction .Y chamber.y Thechamber is preferably insulated by well .known means, not shown in thedrawing, to prevent the excessive loss of heat by radiation and thusmaintain the vapors at aY suitablyhigh conversion temperature duringtheir passage through this zone.

When, as previously described, the heatedoil from heating coil Il)isfdischarged intothe ,lower portion of chamber I4 through line I2 andvalve I3, separation of the major portion of the residual liquidconversion products from the vaporous conversion products is quicklyeffected and the residual liquid withdrawn from the lower portion of thereaction chamber through line..ll tand valve I8 while still in a highlyheated state, without being subjected to appreciable further con?version time in the reaction chamber, andi is dis,- charged at reducedpressure through line I9 into coking chamber 20. In this case vthevaporous v conversion products separated from theresidual liquid in thelower portion of the reactionchamber are subjected to continuedconversion` time as theypass upward through the chamber,.being withdrawnfrom yits upperportion through. line 2| and preferably passing, as hereillustrated,1 through valve 22 into the lower portion of ook-ing chamber20, although theymay be introduced into the coking chamber at anydesired point or may be commingled with the residual liquid, prior toits introduction into the coking chamber or, when desired, may pass allor in part fromthe reaction chamber directto fractionationby Well knownmeans not illustrated.

When the heated oil from heating coil I 0 isy introduced, as previouslydescribed, throughline I5 and valvel l5 into the upper portionof chamberI 4, the vaporous conversion products, being lighter than the residualliquid, may pass down- Award through the chamber more slowly than '6o Ycokc-formingA materials are condensedand separated rfrom'the vapors;VThe tars and similarV *Y Vthe residual oil, being thereby subjected toak longer conversion time in the reaction chamber than ,that affordedthe residual liquid conversion products. In this case both vaporous andresid-V ual liquid conversion products having passed 1 through chamberI4 arepreferably withdrawn in* commingled state through line I1L andvalve` I 8 and directed through line I9 'into the reduced pressurecoking chamber 20. Y `In the case here illustrated, the latent heatliberated by the reduction of pressure in chambery 20, relative tothatemployed in chamber I4`as` sistedby the partial pressure eiect ofthe `vaporous products from the upperrportion of chamber whichl thevapors may impart to the residual i4, passing upward through the bodyofresidual oil in the coking chamber,r aswell as by anyheat liquid, servesto reduce the residual liquid conversion products fromchamberfM tocokein; chamber 20. It is, ofi course, within thescope Y ofthe presentinvention to employ any other well known means of insuring coking of theresidual liquid 1 conversion products in chamber 20 although, for thesake of simplicity, other means are not illustrated.` The coking chambermay, for example, be externally heatedV or a suitable heat Acarryingmedium, Vsuchg'as a light final or intermediate conversionvproduct ofthe process or suitable light oil from an external source, heated iro toa high temperature may be introduced'intok directcontact with thematerial undergoing cokingfin the coking chamber.Y It is also'possibleto assist cokingrbyrthe introduction of `airwor other oxidizing gas toeffect partial combustion and increase the temperature in thecoking'zoneor," heated relatively inert gases such as hot combinationgas may be`supplied to thei coking zone.;V Y y Coke is allowed to accumulatewithin chamber 2i)- to be removedtherefromv after theroperation of thechambery hasbbeen' completed or, preferably, a plurality of cokingchambers similar-to Y chambr Nibut riitilliisirated 'in "the drawing. YVvare employed andm'ayjibelalternately operated J while achamberpreviously ffilled withcoke is lbeing. cleaned and prepared for furtheroperation, thus providing an' unlimited spaceY for vthe depositionfofcoke. V( Jhamber 20'is provided with a drain-'line 23j 'controlledk V,byvalve"24"which mayal'solserve as ajmeans'of introducing steam, water'or4other suitablecooling medium into the chamber, after it `has beenisolated from the system, :to hasten cooling and permit cleaning of `thetubes. Y

Vaporcus products, including tars and similar high coke-formingmaterials 'vaporized under the f cokingconditionsjemployed andi/orcarried over with the' VVvapors by entrainrnent,arewitlidrawn from'thecoking chamber4 through *line Y2 5 and valve 26 to a tar-separatorN:whereinVT said vheavy 1 high coke-forming materials are withdrawn fromthe lowerY portion of separator -21 through line 281-andvalve 29to .pump3l) by meansof whichk theyare returned through line'3lr, valve 32V and.linelB to coking chamber 20 for further heating and reduction to coke.AThey may of courseV be n* separately introduced' into chamber 20 whensubstantially' Yfreed Vof heavy` coke-'forming lnia Y "desired'bywellknown lmeans which are Ynot illustrated.' Y

"Vaporous 'products from fthe VVcokingV chamber terials in separatorV2f! are :withdrawn fromthe upperportion 'of'V this Zone through line33V and partially cooled by indirect contact and heat exchange with theoil being supplied to heating coil means of line and valve36`.to.tarseparator I0. f YCondensate resultingV from Vcooling of thevapors in heat .exchanger1 is returned by 1 `valve 34 to heat exchanger1 wherein they are i 21 wherein itY is substantially revaporizedby'direct contact/With vaporous products from the coking chamberjse'rvingas a'means of cooling the f vapors and effecting the condensation andremoval of the heavy tars and'similarv high cokeformingY materialstherefrom.V c Y ,Y

The partially cooled vapors substantially freed of deleterious Yheavymaterials pass fromV heat exchanger 1V through line 31 to fractonator 38wherein-their insuiciently converted vcomponents are condensed asreiiuxicondensate. ',The reflux condensate removed from the vapors infractionator38 'collects intheflower portion of this zone and iswithdrawn therefrom through line 39 and valve 40 to pump V4| tobereturne'dithere-r from to heating Vcoil I0 for further conversion." Inthe case illustrated, the reflux condensate is' directed from pump 4lthrough line'42 Yand valve 43Vinto line 4, commingling therein with theraw oil charging stock from r'purnp 3 and passing therewith through heatexchangerV 1, line'V and.V

valve 9 VtoV heating coilv I0. It will beunderstood that the refluxcondensate may, when desired, be returned to the heating coil inany wellknown manner not illustrated in the drawing. It is also within the scopeof the'invention to utilize Y a portion of the reux `condensate yoraportion of the rawk oil charging stock orvjarmixture thereof as acoolingmediumA intarsepar'ator 21,

particularly in case heat exchanger 1 is not uti` lized or in case thecondensate from this zone is not sufiicient to effect theVdesiredfseparation in tar-separator 21. Suitable means for theintroduction of'such materials intoseparator 21` are Wellknown' andarenot here illustrated. I

, Fractionated vapors of vthedesired lend-boiling pointk aregremovedftogether',with uncondensable v' i gas, Iffromv the upperportion fof fractionator 38A f through line 44 Vand valve-45,5 aresubjectedto condensation'andcooling in condenser 46,'from :whichtheresulting'distillate*and uncondensable gaspasses through 'line 41'andvalve 48 tore-V Y Y ceiver 49. 'Uncondensable gas may be released I 'i ffromreceiver- 49 ,throughv yline 50 and'valve 5|', VDistillate Vmay be"withdrawn from'this zone through line 52 and'valvef-i'lV .YA portion ofth'e distillate from receiver 4$fmay,'when desired, be

recirculated, by well known meansl notjillustrated Y n vin the drawing,to the upperv portion ofrf-riction-` ator'38 toserve'as a coolingfandfreiiuxing medium y in this zone,1to assist in maintaining ,thedesiredV Y Y vaporfoutlet' temperature fromV the .fractionator, f 'Inaprocesslofthejcharacter illustrated and* 1 above described, 'preferredoperatingV conditions;

maybe as'follows I pressure ranging, for example, from pounds,

or thereabouts, per sq. in. downV tosubstantially atmospheric pressure.Preferably'the .vaporous products entering the fractionator of thesystem are cooled to a temperature of about 750 F. or less, in order toprevent the return of any appreciable amount of material boiling abovethis temperature to the heating coil.

As a specic example of the operation of the process of the presentinvention, let us rst consider an operation similar to that abovedescribed except that the features of the present invention are notutilized. The raw oil charging stock is a 30 A. P. I. gravityMid-Continent topped crude which is subjected together with the totalreflux condensate, including heavy tars, from the coking operation to aconversion temperature of approximately 935 F. at a super-atmosphericpressure of about 350 pounds per sq. in.l Substantially this samepressure is maintained in the reaction chamber, residual liquid beingquickly separated from the residual products in the reaction chamber andwithdrawn to alternately operated coking chambers maintained at apressure of about 20 pounds per sq. in. while vaporous productsseparately Withdrawn from the upper portion of the reaction chamber, arepassed upward through the bed of residual material in the cokingchamber. This operation may yield, per barrel of charging stock, about62 percent of motor fuel having an antiknock value equivalent to anoctane number of approximately '74, the additional products of theprocess being about 90 pounds of coke and about 700 cubic ft. ofuncondensable gas per barrel of charging stock. The process may beoperated continuously over a period of from 2 to 3 weeks and is shutdown, almost invariably, due to the deposition of coke in the heatingcoil.

In another operation similar to that just described except that thefeatures of the present invention are utilized and heavy tars areseparated from the vapors, prior to their fractionation by cooling themto a temperature, measured at the inlet to the fractionator, of about730 F. and returning said heavy materials to the coking chamber, atemperature of about 950 F. may be safely employed at the outlet fromthe heating coil but the other operating conditions are maintained aboutthe same as those above given. This operation may produce about the sameyield of motor fuel, based on the raw oil charging stock, but itsantiknock value may be increased to an octane number of approximately78. A somewhat lower yield of coke of lower volatile content is producedas compared with the operation first described and the production of gasis slightly increased. In addition to the advantages of better antiknockmotor fuel and lower volatile coke, the improved process of the presentinvention permits an operating cycle 2 to 3 times as long as thatpossible when the features of the invention are not employed.

I claim as my invention:

A conversion process which comprises heating hydrocarbon oil to crackingtemperature under pressure in a heating coil and then discharging thesame into an enlarged separating zone, separating vapors fromunvaporized oil in the separating Z'one, introducing the unvaporized oilto the upper portion of a coking still and distilling the same to cokein this zone, removing separated vapors from the separating Zone andintroducing the same to the lower portion of the coking still to passupwardly therethrough in countercurrent contact with the unvaporizedoil, separating from the coke still vapors tars and similar highcokeforming materials and returning the same to the coking still Withoutprior heating thereof to cracking temperature, fractionating theremaining coke still vapors and supplying resultant reux condensate tothe heating coil, and finally condensing the fractionated vapors.

JOSEPH G. ALTHER..

